In an expected and inevitable move, Microsoft has announced that the next version of Office will include Web-based versions of Word, Excel, Powerpoint, and OneNote.

Not to be confused with Microsoft Live Office Workspaces, which lets users of the desktop Office suite collaborate online, Office Web Apps will be full lightweight versions of the products, allowing users to create, edit, save, and share docs on the Web. And, like obvious competitor Google Docs, Office Web Apps will be available for free.

Like Docs, which requires a Google account, it seems the only requirement to use Office Web Apps will be a Microsoft Windows Live account, with two other options as well:

“Office Web applications will be available in three ways: through Windows Live, where more than 400 million consumers will have access to Office Web applications at no cost; on-premises for all Office volume licensing customers including more than 90 million Office annuity customers; and via Microsoft Online Services, where customers will be able to purchase a subscription as part of a hosted offering.”

Unfortunately, there isn’t anything to try out yet – Microsoft says that the new version of Office and its accompanying Web version won’t be available until the first half of next year. For now, the company has launched a preview site and a series of videos, introduced below:

• See What’s New in Microsoft Office 2010

  Update: The embed from Microsoft seems to be loading sporadically. Here’s an interview that Robert Scoble has with Office 2010 Product Manager Chris Bryant demoing some of the Web features (more on his blog):